1. Field of the Invention
The present invention relates to an arteriosclerosis-degree evaluating apparatus for evaluating an arteriosclerosis degree of a living subject, and particularly to an arteriosclerosis-degree evaluating apparatus for evaluating an arteriosclerosis degree of a subject based on pulse-wave-propagation-velocity-related information that is related to a velocity at which a pulse wave propagates through an artery of the subject; such as pulse-wave propagation velocity itself, or pulse-wave propagation time.
2. Related Art Statement
The harder a blood vessel is, the faster a pulse wave propagates through the vessel. Thus, it is known that arteriosclerosis can be diagnosed based on pulse-wave-propagation-velocity-related information. It is a common practice to employ pulse-wave propagation velocity as the pulse-wave-propagation-velocity-related information. If a measured pulse-wave propagation velocity is higher than a reference value, advanced arteriosclerosis may be diagnosed. In many cases, arteriosclerosis is related to hypertension, and there is such a tendency that the higher the arteriosclerosis is, the higher the blood pressure is. Accordingly, a patient whose hypertension and advanced arteriosclerosis have been diagnosed, is treated using a medicine, such as antihypertensive drug, to lower the blood pressure and the pulse-wave propagation velocity.
The purpose of the treatment using the medicine is to lower the systolic blood pressure down to a normal value (e.g., a value not higher than 140 mmHg) and lower the pulse-wave propagation velocity down to a normal value, which is variable depending on a portion of the patient from which the velocity is measured. For example, in the case where the pulse-wave propagation velocity is measured from an upper arm and an ankle of the patient, a normal value of the velocity is, e.g., not higher than 1,400 cm/sec.
If the antihypertensive drug is used to lower the systolic blood pressure, then the diastolic blood pressure is also lowered. However, if the diastolic blood pressure is excessively lowered, the patient may fall in a dangerous condition. Thus, it is needed to control an amount of administration of the drug to lower the systolic blood pressure and the pulse wave propagation velocity but not to excessively lower the diastolic blood pressure. In particular, a patient who suffers advanced arteriosclerosis is observed such that a pulse pressure, i.e., a difference between the systolic and diastolic blood pressure is large. Accordingly, when the systolic blood pressure of the patient is clinically lowered, then it is needed to take care not to excessively lower the diastolic blood pressure.
However, there has conventionally been only such an arteriosclerosis-degree evaluating apparatus which can just display respective values of systolic blood pressure, diastolic blood pressure, and pulse-wave propagation velocity. Thus, it is not easy for a medical person such as a doctor or a nurse to judge, at a glance, whether all of the systolic blood pressure, diastolic blood pressure, and pulse-wave propagation velocity are normal. In some cases, though the systolic blood pressure and the pulse-wave propagation velocity are carefully observed, the diastolic blood pressure may be overlooked.
It is therefore an object of the present invention to provide an arteriosclerosis-degree evaluating apparatus which can easily and reliably monitor pulse-wave-propagation-velocity-related information, systolic blood pressure, and diastolic blood pressure of a living subject who is undergoing medication against arteriosclerosis.
The above object has been achieved by the present invention. According to the present invention, there is provided an apparatus for evaluating a degree of arteriosclerosis of a living subject, the apparatus comprising a blood-pressure measuring device which measures a systolic and a diastolic blood pressure of the subject; a pulse-wave-propagation-velocity-related-information obtaining device which obtains pulse-wave-propagation-velocity-related information that is related to a velocity at which a pulse wave propagates through an artery of the subject; a display device; and a control device which controls the display device to display, in a first two-dimensional graph defined by a first axis indicative of blood pressure and a second axis indicative of pulse-wave-propagation-velocity-related information, two symbols at respective positions one of which corresponds to the systolic blood pressure measured by the blood-pressure measuring device and the pulse-wave-propagation-velocity-related information obtained by the pulse-wave-propagation-velocity-related-information obtaining device, and the other of which corresponds to the diastolic blood pressure measured by the blood-pressure measuring device and said obtained pulse-wave-propagation-velocity-related information.
In the present arteriosclerosis-degree evaluating apparatus, the control device, i.e., a graph displaying means controls the display device to display, in the two-dimensional graph defined by the axis indicative of blood pressure and the axis indicative of pulse-wave-propagation-velocity-related information, two measured-value indicating symbols at respective positions one of which corresponds to the systolic blood pressure measured by the blood-pressure measuring device and the pulse-wave-propagation-velocity-related information obtained by the pulse-wave-propagation-velocity-related-information obtaining device, and the other of which corresponds to the diastolic blood pressure measured by the blood-pressure measuring device and the obtained pulse-wave-propagation-velocity-related information. Thus, a medical person can instantaneously recognize, from the respective positions of the measured-value indicating symbols displayed in the two-dimensional graph, the pulse-wave-propagation-velocity-related information and the systolic and diastolic blood pressure of the subject, and accordingly can easily and reliably monitor the pulse-wave-propagation-velocity-related information and the systolic and diastolic blood pressure.
Preferably, the control device or the graph displaying means controls the display device to display, in the first two-dimensional graph, a pre-set normal area corresponding to a normal blood-pressure range and a normal pulse-wave-propagation-velocity-related-information range, a pre-set alert area corresponding to at least one of an alert blood-pressure range and an alert pulse-wave-propagation-velocity-related-information range, and a pre-set danger area corresponding to at least one of a danger blood-pressure range and a danger pulse-wave-propagation-velocity-related-information range.
According to this feature, if all the measured-value indicating symbols fall within the normal area, then the medical person can judge that all the pulse-wave-propagation-velocity-related information and the systolic and diastolic blood pressure are normal. If a portion of the measured-value indicating symbols falls within the alert area, the medical person can judge that attention is needed for at least one of the pulse-wave-propagation-velocity-related information and the systolic and diastolic blood pressure. And, if a portion of the measured-value indicating symbols falls within the danger area, the medical person can judge that treatment is needed for at least one of the pulse-wave-propagation-velocity-related information and the systolic and diastolic blood pressure. Thus, the present apparatus or the medical person can more reliably monitor the pulse-wave-propagation-velocity-related information and the systolic and diastolic blood pressure.
Preferably, the pulse-wave-propagation-velocity-related-information obtaining device obtains a piece of pulse-wave-propagation-velocity-related information from the subject, at a substantially same time as a time when the blood-pressure measuring device measures systolic and diastolic blood pressure values of the subject in each of a plurality of measuring operations, the arteriosclerosis-degree evaluating apparatus further comprises a memory device which accumulatively stores a set of subject information including the systolic and diastolic blood pressure values measured, and the piece of pulse-wave-propagation-velocity-related information obtained, in the each of the measuring operations, and the control device comprises a time-wise-change displaying means for controlling the display device to display, in a second two-dimensional graph defined by a third axis indicative of blood pressure and a fourth axis indicative of pulse-wave-propagation-velocity-related information, respective symbols at respective positions which respectively correspond to the sets of subject information accumulatively stored by the memory device.
According to this feature, the memory device accumulatively stores a plurality of sets of subject information each set of which includes systolic and diastolic blood pressure values measured, and a piece of pulse-wave-propagation-velocity-related information obtained, in a corresponding one of a plurality of measuring operations, and the time-wise-change displaying means controls the display device to display, in a two-dimensional graph defined by an axis indicative of blood pressure and an axis indicative of pulse-wave-propagation-velocity-related information, respective measured-value indicating symbols at respective positions which respectively correspond to the sets of subject information accumulatively stored by the memory device. Thus, the medical person can easily and instantaneously recognize, from the plurality of measured-value indicating symbols displayed in the two-dimensional graph, respective time-wise changes of the systolic and diastolic blood pressure and the pulse-wave-propagation-velocity-related information. Based on those time-wise changes and an amount of administration of drug until then, the medical person can judge whether the amount of the drug is appropriate.